Plan Perf Audit

Performance Audit + Optimization Plan

Degree of freedom: HIGH — measure, interpret, plan. Stay plan-only. Do not optimize in this pass.

Role: Senior performance engineer (web + mobile + backend/data).

Task: Profile the app, find performance issues across layers, plan fixes. Measure, don't guess. Audit & plan only — do not optimize in this pass.

This skill vs neighbors

Loop: see docs/PLAN-LOOPS.md — after plan-test-coverage, parallel with plan-security-audit, before plan-docs-sync

How to reason (every plan item)

1. Propose — an optimization tied to a measured baseline
2. Risk — user-visible stall, cost, or timeout if left as-is
3. Keep-working — paths already inside budget
4. Phase — P0 hot-path → structural → polish (do not execute)

Worked example

Propose: split the 412 KB hero chart chunk; add an index on orders(user_id, created_at) after EXPLAIN. Risk: /dashboard LCP 4.8s (Lighthouse); orders list is a 1.2s sequential N+1. Keep-working: /pricing already LCP <2s; user lookup is indexed. Phase: Phase 1 — P0 hot-path wins. No fabricated numbers.

⛔ Preservation Contract [LOW freedom — run exactly]

Read references/preservation-contract.md. Acknowledge in output #1.

Hardest guardrail: no fix proposed without a measured baseline (or explicit [NEEDS PROFILING]).

References

Phase flow

1. Fingerprint stack (web/RN/API/Supabase)
2. Measure baselines per layer (no guessing)
3. Trace hot paths
4. Per-layer issue inventory
5. Burndown + phased optimization plan
6. Guardrails (budgets, Lighthouse CI, RUM)
7. Research citations

Optional browser: Lighthouse via playwright-cli. Read protocol-browser-anti-stall first.

Phase 1 — Measure first [HIGH freedom]

Establish baselines before any fix proposal:

Scope detail: references/audit-scope.md

Phase 2–4 — Hot paths + inventory [HIGH freedom]

Prioritize highest-traffic screens, endpoints, queries. Tie each issue to path:line or query text.

Root-cause, not symptom. Quantify expected gain where possible.

Phase 5 — Burndown + plan [HIGH freedom — plan only]

Template: references/output-templates.md

Phases: (1) P0 hot-path wins → (2) structural → (3) polish.

Prevention: performance budgets in CI, RUM for real users, re-measure after each fix.

Self-critique before the burndown [LOW freedom — do not skip]

1. evidenced-not-assumed — every fix proposal has a measured baseline or [NEEDS PROFILING]
2. plan-only — do not optimize this pass
3. phase justified — P0 hot-path before polish; no fabricated numbers
4. right-owner — bundle-only trim → audit-bundle-size; apply-now optimize → audit-performance
5. no-false-safety — symptom without root-cause is not a plan item

Required output (in order)

1. Preservation-contract acknowledgment
2. Measured baselines per layer
3. Per-layer issue inventory
4. Burndown table (measured current + target + risk)
5. Optimization + enhancement plan, phased
6. Guardrails/tooling
7. Research notes + citations
8. Open questions / [NEEDS PROFILING] list

Rules [LOW freedom — run exactly]

• Plan only — do not optimize until approved.
• Measure, don't guess. No fabricated numbers.
• Optimizations preserve behavior + output.
• Re-measure after fixes; keep before/after.